


good reasons to freeze to death

by cashtastrophe



Series: goddamn, we missed the vein [3]
Category: Undertale (Video Game)
Genre: Alternate Universe - Swapfell (Undertale), Alternate Universe - Underfell (Undertale), Alternate Universe - Underswap (Undertale), Angst, Child Abuse, Explicit Sexual Content, F/F, F/M, Fellcest - Freeform, Fontcest, Hurt/Comfort, Implied/Referenced Child Abuse, Incest, M/M, Murder, Parent/Child Incest, Rape/Non-con Elements, Sexual Abuse, Sibling Incest, Swapfell Papyrus (Undertale), Swapfell Sans (Undertale), TECHNICALLY IT IS COMING, Tentacle Sex, Underfell Papyrus (Undertale), Underfell Sans (Undertale), Underfell W. D. Gaster, Underswap Papyrus (Undertale), Underswap Sans (Undertale), Underswap W. D. Gaster, edgeberry, honeymustard - Freeform
Language: English
Status: In-Progress
Published: 2021-02-26
Updated: 2021-02-28
Packaged: 2021-03-17 16:15:50
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Major Character Death, Rape/Non-Con, Underage
Chapters: 2
Words: 9,064
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29719857
Author URL: https://archiveofourown.org/users/cashtastrophe/pseuds/cashtastrophe
Summary: “Fuck you and fuck your mom and fuck your recovery,” the other sans snaps, coming to a halt only a few paces away with his face twisted towards Sans where he’s perched at the foot of the bed.His eyelights are practically pulsating,  molten hot pink with rage.  Nonsensically, Sans registers that it’s a really pretty color. “Were you even listening to me, you little nutjob? I killed Gaster to protect my brother. Now riddle me this, asshole: why wouldyourbrother, the laziest fuck in the Underground, plot and execute awhole entire murderwith a girl he barely knows?”(Act Two, or: Blue goes on a road trip across time and space to salvage what’s left of Edge.the direct sequel to ‘little blue pills’ and dealing with the events in ‘everyone learns faster on fire’)
Relationships: Papyrus & Undyne (Undertale), Papyrus/Sans (Undertale), Sans & Sans (Undertale), W. D. Gaster/Papyrus, W. D. Gaster/Papyrus/Sans, W. D. Gaster/Sans
Series: goddamn, we missed the vein [3]
Series URL: https://archiveofourown.org/series/492898
Comments: 15
Kudos: 26





	1. prologue: apartment

**Author's Note:**

> Blue’s on a mission to offer Edge a chance to not be an asshole and also he is totally fine!!!!
> 
> please see the end notes for trigger warnings but y’all should have SOME idea of what to expect from me by this point maybe 
> 
> also it’s lowkey a songfic now and I’m barely sorry

# prologue

* * *

_I stared out the window_  
_hands glued tight and sore_  
**_praying to god knows what_**  
**_that you would sever what’s stuck_**  
_with something shiny from the kitchen drawer_  
  
—modern baseball, _apartment_  
  


* * *

  
There’s no good way for Sans to ask the question.  
  
And it might be overkill to even try on his part, honestly, because the shadow lurking in the corner of his little episodes (he staunchly refuses to call them _visions_ , thanks, he’s not a fantasy-novel protagonist) didn't exactly communicate a game plan.  
  
It didn't tell him, in any sort of explicit terminology, what it was after. What it wanted. Why, out of everything that's happened to them already, it chose to show _him_ those very specific snippets of an evil baby edgelord Papyrus at two of the worst moments of his life...and completely recontextualize every single unkind thought Sans has ever had regarding his counterpart's brother in the process.  
  
It was one thing, hearing the other sans's stilted recollection of the night Papyrus had raped him on a stranger's bed, and quite another to temper his instinctive flare of rage long enough to consider the fact that Papyrus had been _sixteen_ at the time.  
  
He'd been a child still himself, barely a few years out of stripes, and Sans definitely isn't making excuses, but—  
  
Sans just...can't quite seem to stop himself from remembering his own Papyrus at that age: anxious and always wired, snapping at everyone around him by default, vicious-drunk nearly every night he could get away with it, seemingly held together by little more than spite and a constant, slow-simmer rage.  
  
(( He can't stop thinking about plates smashing against the kitchen walls, and his own shaking claws barely able to keep hold of the broom and dustpan. He can't stop thinking about the way his vision would sometimes go staticky and grey with terror, how his breath would catch in his aching chest listening to Gaster and Papyrus screaming at each other from the next room over— listening intently for the dull thud of a body colliding with drywall again, though he never could do anything to stop it.  
  
He would just answer the door, when the neighbors came knocking, and he would smile, and he would reassure them that of course he’d tell his family to keep it down. He would lie through his wicked teeth and tell them that no, nothing was wrong, just teenaged tempers run up broadside against the stress of being a single parent, _you know how they can be, you understand,_ whatever useless platitude would make them drop the issue. Apologies after apologies, tripping over himself with how sorry he always was—but none of it for the monster that really deserved it the most.  
  
He would do nothing at all to help his brother, in short, and still his own Papyrus is so hideously grateful for his presence. Still, his own Papyrus will tell him these awful private things when he’s blackout drunk: wobbly, shameful little secrets like _you saved me, you know that, without you I probably never woulda made it this long_ and he will pointedly never clarify when Sans asks him what the fuck _that_ means, exactly.  
  
They both know perfectly well anyways, even if neither of them ever manages to say it aloud. Sans is pragmatic enough to understand the impulse on some level, his brother’s aching brain seeking any available relief, even if it makes a sucking horror open up in the very center of his soul, panic flooding his whole body at the idea.  
  
He can't picture his world without Papyrus. He doesn't _want_ to, he doesn't even want to consider how empty the house would echo with his brother gone. But even if his mind skitters around the topic like an insect avoiding the coils of a hot stove, he also can't stop wondering what that particular predisposition means for the other Papyrus, exactly.  
  
Did he lie motionless on his mattress, too, staring at his bedroom ceiling and praying for the world to end? Did he have scratches clawed all down his forearms, stark enough—embarrassing enough— that he never pushed his sleeves up in mixed company either?  
  
Did he wake up most nights choking on the screams he couldn’t quite force himself to swallow? Did his soul pound sometimes like it was trying to rip its way straight out of his ribcage, did it leave him shaken and shaking and scared and flinching at his own shadow and if it did—  
  
Had he _ever_ had someone help him through it?  
  
The other Papyrus had looked so small, curled up in that damp Waterfall cave. He had looked so painfully young.  
  
He had _been_ so painfully young.  
  
He’d been twelve years old, and _he had not deserved what had happened to him. ))_  
  
There’s no excuse, Sans tells himself firmly, but there are _reasons_. His own Papyrus’s bad habits didn’t occur in a vacuum, after all, and he’d had at least _some_ measurable degree of support, even if Sans is well aware of his own missteps in that regard.  
  
How badly would Papyrus have cracked under the pressure if he’d never had anyone to hold his hand through the worst of it at all? If his very definition of ‘worst’ had been cranked up to eleven, in fact, and he had subsequently been left to mire through it alone?  
  
So then by extension...doesn't someone owe it to the other Papyrus to at least _try?_  
  
  
  
  


* * *

  
  
  
  
He doesn't manage to bring himself to ask if sans knew about the website, exactly. He doesn't manage to spell it out in any real detail. He can't come up with any way to do it that doesn't reveal far more than he'd want to, in case sans has been kept entirely in the dark about that particular dirty little secret.

He hasn't actually met the other Papyrus yet, and even still he's certain that he owes the guy that small courtesy.  
  
Instead, he settles on: “So...your brother started working pretty young, right?”  
  
The other sans is sprawled across the bed on his belly, buried in a book he’d borrowed from Papyrus. He’s been parked there for the past hour at least, apparently engrossed with the tattered pulp sci-fi novel, its cover torn off and a healthy crop of _Aspergillus sp._ decorating its broken spine. He’s sneezed sixteen times that Sans has counted.  
  
“We both did,” he says without looking up, or any inflection at all. “Once Pap started spending so much time out of the house and bringing in some gold, it just kinda made sense for me to pick one up, too. Or three,” he allows with a faint smirk at his own wordplay, turning the page. “Raising a teenager’s expensive, and the more the doc lost it, the—uh, the more Core-sick he got, you know?—the less he remembered shit like, I dunno, the whole ‘payin’ rent on time’ concept.” He shrugs. “Plus, being stuck alone with him was...not ideal,” he offers after a beat, biting the _t_ sound off as though it had personally offended him.  
  
Sans desperately doesn't want to ask for details, but he's learned his doppelgänger well enough to know that little sliver of vulnerability _might_ have been a deliberate test.  
  
He's so closed off when he wants to be, so careful to play his cards so _frustratingly_ close to his chest that he rarely exposes anything without meaning to—though it's admittedly difficult to read his intention when he's this diligent in avoiding Sans's gaze, either way.  
  
Still, where there's a crack, Sans has found he often opens up willingly with a gentle nudge, and that is a marked improvement over the half-feral paranoid suspicion that had practically oozed out of him when he'd first arrived.  
  
It's almost as though he's beginning to believe, at least a little bit, the constant reassurances that Sans _wants_ to help carry the weight of his personal albatross.  
  
((It’s a step.  
  
It’s a step Sans is going to blow straight to hell within the next forty-eight hours by fucking off to his home nightmare dimension and abandoning him to Papyrus’s tentative grasp on functional adult behavior—but it’s still a step.  
  
He’s counting it. That’s _progress_.))  
  
“Was he...worse with you, the sicker he got?” Sans asks softly, fully prepared for his counterpart to shut down under the scrutiny. Instead, he’s pleasantly surprised to find that those dim pink eyelights flick towards his face, perhaps searching for a trace of pity in his expression.  
  
“Weirder,” the other sans clarifies, when he evidently finds none. He wrinkles his nasal cavity. “He had, like. Straight-up _tentacles_ towards the end of it all, you know? Body couldn't keep itself together under that much exposure to the Core, I guess. His face and his hands stayed okay for the longest time, so he could at least sign once he'd lost his voice, but...they'd started to melt too by the time he finally bit it.”  
  
Softer, brow ridge furrowing, he continues. “He _really_ liked to fuck by those last few weeks though, which was kinda strange—it must have been something about all that neural feedback, it anchored him in that body somehow. He was always more coherent for a while, after.” Color streaks across his cheekbones faintly when he finally blinks, as though he's only just realized what he'd said. He drops his eyelights back down to his book, shoulders already hunching into his all-too-familiar defensive posture. “It was like bad fetish porn, man. I don't really wanna talk about it.”  
  
“Fair enough,” Sans manages with only a faint strain to his voice, because he’s getting _better_ at this, he’s learning where he needs to be cool and neutral and keep his own feelings out of the equation entirely. He’s learning that his doppelgänger appreciates a sounding board for the most part, but absolutely panics at the idea of his dreadful experiences actually affecting Sans in any real way, so.  
  
The very least he can do is not add to the chaos by, say, putting his fist through the nearest available wall in response— no matter how much he might want to break something at the mere thought of Gaster and his _tentacles_.  
  
Instead, he pulls in several deep breaths through his nasal cavity, and focuses on unlocking his jaw from its rictus clench. Instead, he carefully unfolds his fingers from their instinctive fists, and smooths down the front of his hoodie.  
  
He keeps calm, mostly by sheer stubborn willpower honed by years of strictly-scheduled meditation practice. The other sans studies his own scuffed knuckles quietly and doesn't seem at all on the verge of losing it, so he's guessing the deep-breathing technique must keep him looking relatively unruffled.  
  
“Why you so curious about our work, anyways? Ain’t nothing interesting about us up ‘til Pap got into the Guard, really. Few food service gigs, some courier work, nothing too different from what you got here, I bet.” sans kicks his bare feet behind him like a teenager and folds the corner of his page down to mark his place, abandoning his efforts to read entirely. He pushes himself up into a sitting position, scoots to the edge of the mattress and keeps himself curled tightly, protecting organs he doesn't even have probably on instinct alone.  
  
“Just wondering, I guess!” Sans lies in a perfect chipper little trill. “It really helped my Papyrus, you know? Meeting new people, building new relationships...I think Muffet was the first person besides me he’d heard say anything nice to him in years, he really kinda flourished there. What, uh...what was it like for yours? D’you remember?”  
  
His counterpart considers it for a moment. “He liked it at first, I guess. He wouldn't shut up about it for like, a _week,_ and he wasn't a real excitable kid. I always thought Grillby's old man was a hardass, way he'd tell it, but the dude was nice enough to Pap.” He props his chin on one hand. “Always sent him home with leftovers for us, although Pap stopped eating them pretty quick. He said all the grease made him sick, but I always thought the place maybe stressed him out a little more than he let on. He refused to eat there ever again, from what I remember, even after Grillbs took over and the menu totally changed. I can only imagine the horrors he must've witnessed in that kitchen,” he says with a soft noise that nearly qualifies as a laugh. “A stickler for cleanliness the guy ain't, but he makes a hell of a burger.”  
  
“Grillby?” Sans manages to ask even through his green-grey haze of nausea, certain he knows _exactly_ why Papyrus boycotted the whole establishment.  
  
Certain, just as completely, that his doppelgänger has absolutely no idea what had happened there.  
  
Desperate to offer _something_ to keep the conversation light and normal he says, “We’ve got a fire elemental that runs a little bakery in Hotland with his sister by that name. Any relation, do you think?”  
  
“Probably the same dude,” the other sans agrees, wrinkling his brow in contemplation. “Our Muffet has a tea shop and a terrifying drug empire out that way, so...I guess that makes sense?”  
  
“As much as any of this does, I suppose,” Sans agrees. “Did he work there for very long?”  
  
“Nah—six months, maybe a year, I can't remember exactly. He picked up a few shifts here and there for a while afterwards when things got really tight but Pap started hitting the books pretty hard by that point for his entrance exams for the Academy. He didn't really _need_ to work anyways, since I had the sentry job and everything. I convinced Gaster to hand over the household finances once he got bad enough, and we got by just fine up until he died. Shit got hard again after that, for a while.”  
  
“Yeah,” Sans concurs, low. He remembers those lean years all too well, though it’s only recently that he has the context to fully understand what a shock that must have been for his brother, to go from running a household with their father’s considerable—and more importantly, dependable— paycheck, to a reality riddled with the fallout of Gaster having never existed at all.  
  
Gaster’s disappearance from the mortal plane meant that he’d left no trace behind: no inheritance, no insurance, no worker’s compensation or death benefits, no buffer at all to separate them from their impending debts. Sans recalls all too easily the sharp, familiar ache of hunger in a belly he doesn't even technically have, even all these years later. It was only a stroke of luck that the house had been in Papyrus's mother's name instead.  
  
“You remember,” the other sans confirms with that same fond little crinkle to his eye sockets that he gets every time he notes one of their shared tragedies, some little dark spot where their timelines bleed into each other.  
  
“I remember Papyrus working four jobs while I camped outside Alphys’s place and begged her to train me,” Sans replies, and it's his turn to keep his eyelights downcast, shame burning hot beneath his sternum. “I remember yelling at him about leaving his dirty clothes in the hamper for weeks, because both of us were working morning until night even if only one of us paid any bills with it. I remember telling him he was wasting his potential in dead-end jobs, because I _didn’t understand why he was doing it.”_  
  
“Yeah,” his twin murmurs, “I always wondered if Pap would pull this shit, if he found out. You guys are a lot alike, you know?” but he doesn't say it with any malice, clearly doesn't mean it as an insult even as it makes Sans bristle in outrage. “You're both so desperate to take on the responsibility, you're so eager to be a martyr, you skip right over the fact that me n' Pap are adults, too.”  
  
Sans blinks. “Uh,” he says, but does not get any chance to elaborate.  
  
His counterpart barrels on, louder: “We made our choices, your brother and me. We knew what would happen when we killed Gaster, we _knew_ you wouldn't remember. That was the point. You were supposed to have a chance to live without it, you were supposed to have the chance to be _normal_.” If he had hair he'd be pulling at it, surely, with the agitated sound his claws make scrubbing over the back of his skull. He laughs, and it's a cold, bitter thing spit between his razor teeth. “You were supposed to be happy,” he says and his voice trembles just a little, just enough that Sans knows tears (and their accompanying crisis) are imminent.  
  
What Sans _should_ do is argue. What he should do is tell his twin that he’d missed one glaring flaw in that supposed plan, inform him that whatever the intentions had been, it was downright _cruel_ to strip all of the other Papyrus’s history and motivation from his very concept of himself, since it left him with such a terrible end result but no idea of _why_ he acted the way he did.  
  
He should ask, even if it’s immeasurably hurtful, if sans had ever considered that hollowing his brother out into a shell containing only faceless violence and terror could be part of _why_ Papyrus is so deeply unhinged.  
  
He doesn't. He can't.  
  
Instead, in a tiny, wavering crackle of a voice, his soul suddenly heavy as wet cement in his chest he asks, “Papyrus........killed his dad?”  
  
“Oh, shit,” the other sans winces, eyelights guttering out in black panic. It startles him to his feet. “Oh shit, did he really not tell you? Why the fuck—he told _me_ before he told you?”  
  
“I guess so,” Sans says, numb. He can feel the cement clinging to the backs of his ribs, even if he can't feel anything else.  
  
“I didn’t—I mean, I kind of asked him, I just assumed—it h-had to have been him, since he w-was the only one who remembered his old man, you know? Well, him and U-undyne, I guess she—she must’ve helped with the security footage. The, the cameras, the cameras in my universe they hadn't worked for months and _fuck_ why am I still talking, I just—I'm really sorry dude, are you okay?”  
  
Sans isn't. Sans isn't sure if he'll ever be okay again, because now he has to backtrack through a whole shared history and scrutinize his brother for that budding, terrifying potential. He has to look at the same monster who routinely falls asleep in front of cooking shows with one hand still stuck in an open bag of chisps, and somehow contend that image with one where Papyrus had consciously chosen to murder his own father.  
  
His whole world sits six degrees to the left now, and he is—  
  
He is not coping.  
  
“He—he doesn't have any LOV,” Sans says desperately, knowing full well that he's grasping at straws. “How—he'd tell me if he did, they wouldn't allow him to keep being the Judge if he did!” _You must be wrong,_ he doesn't say, but the intent comes across pretty clear regardless.  
  
“It didn't give me any, either,” the other sans says a bit more gently, shrugging one shoulder. “I guess since technically he just blipped outta existence, it's not like I actually attacked him. It didn't seem to count. Seriously, are you alright? I've _never_ seen your eyelights go out before.”  
  
Sans laughs, entirely without meaning to, and his counterpart’s sockets narrow in suspicion. “Tell me how you did it,” he requests, instead of explaining the joke and subsequently ruining what had made it funny in the first place.  
  
(( Instead of asking how his own brother had done it. ))  
  
“Shoved him into the Core,” his doppelgänger says, flat, eyelights locked firmly on his face. “And I'm not sorry for it. You wanna know why?”  
  
Desperately, Sans does. Desperately, he needs _something_ to slot into the new cracks that have formed in his mental image of his brother, some information to patch over the wounds and try to make some sense of it all. He nods frantically, mouth too dry to speak.  
  
“I wasn't a lot of fun for him, towards the end. Turns out, if you keep on throwin' the same plate at the ground and just gluing the pieces back together, you eventually wind up with somethin' that's pretty damn useless as a result.” He shoves his hands deep into his sweatpants pockets, and glares at the poster behind Sans's head, voice measured and flat like he isn't describing something straight out of a horror movie. Sans hopes it makes the recollection a little easier, because the visible fight for dissociation makes it _way_ harder to watch. “I didn't cry or scream or fight anymore. I hadn't, for years probably. I just sorta...laid there and let it happen. It pissed him off bad, too, and that kinda made it all worth it.”  
  
He _never_ goes into this kind of detail voluntarily. He never talks about how he felt during, though Sans has never been acutely aware of that absence before. He’s never once described more than the barest shape of events, all allusion and polite gaps and none of the ragged, festering flesh of the violation itself.  
  
“Get that look off yer face,” the other sans growls, accent twanging a little more harshly against his consonants the way it always does when he’s embarrassed. His shoulders hitch up just the barest degree. “I ain't doing this if you're gonna give me the kicked-puppy thing the whole fuckin' time, bro.”  
  
Sans fights to school his expression into something cool and neutral, fights to remember his breathing. He drags a shaky breath in through his nasal cavity, but he still feels like he’s choking on it. “Sorry,” he rasps, and means it so much that his chest aches. “Sorry, please, just—tell me what happened. _Please_.”  
  
“I caught him in Pap’s room,” the other sans says, almost too softly to hear. “We had—we had an arrangement, you know? I cooperated, and he left the kid alone. He wasn't allowed to be in there at night, much less with the door closed. Much less— ” his voice breaks, and he's suddenly moving, bare feet pacing the faded carpet as though he's a shark, and it would kill him to keep still. “I stopped him before anything happened. He just....touched Pap, I guess, but Pap stayed asleep the whole time. He didn't know. I got there in time. I—I _cooperated_ for him that night, and then I pushed him into the Core the very next day. _That's_ why I'm not sorry. I had no other way to stop it from happening again.” He reaches the nearest wall and makes an abrupt u-turn, stalking back towards the mattress with his gaze still fixed somewhere faraway.  
  
“Gaster would have raped him too,” Sans offers in spite of the way it makes his doppelgänger flinch. He’s used to pushing past that twinge of guilt by now. “So you killed him before he got the chance.”  
  
“You know how I feel about using that word,” the other sans growls. “We had an _arrangement_.”  
  
“An arrangement where he had carte blanche to _rape you with his tentacles_ so long as he left your little brother alone. It’s important in recovery to acknowledge the gap between your own perception and what was actually occurring.”  
  
“Fuck you and fuck your mom and fuck your recovery,” the other sans snaps, coming to a halt only a few paces away with his face twisted towards Sans where he’s perched at the foot of the bed.  
  
His eyelights are practically pulsating, molten hot pink with rage. Nonsensically, Sans registers that it’s a really pretty color. “Were you even listening to me, you little nutjob? I killed Gaster to protect my brother. Now riddle me this, asshole: why would _your_ brother, the laziest fuck in the Underground, plot and execute a _whole entire murder_ with a girl he barely knows?”  
  
Oh.  
  
Oh, _no_.  
  
“Yeah, sweetheart, _there_ it is,” his doppelgänger sneers with a sort of vicious glee. “So why don'tcha go ask your brother why he loves you enough to kill his own dad to keep the family dog safe? Why don't you go ask _him_ what Gaster was gonna do to _you_ , and then you sit there and tell him he was wrong for protecting you the only way he knew how. You think any 'a that was _easy_? You think that was a simple decision for him to make? Fuck you and the high horse you rode in on, Sans. Your brother would _die_ for you.”  
  
Which is. Which is _fair_ , more than fair, even if the delivery wasn't exactly gentle, even if it steals the breath from lungs he doesn't have. “You're right,” he croaks, only barely registering the sting in his sockets that means they're welling up with tears. “You're right, I didn't— I didn't understand,” he manages, barely, and his voice breaks and the tears fall and his chest _hurts_ and he feels like he's dying, and there's not a thing in the world he can do to stop any of it, really. “Now I do.”  
  
“Aw fuck,” his doppelgänger murmurs, his expression easing into something softer and a perhaps a little pained. His eyelights dim to their usual affectionate rose. “Hey, I didn't mean to make you cry, I— _oof_ ,” he grunts as Sans rockets into his chest, burying his wet face in the curve of the other sans's shoulder and wrapping his arms around the much-smaller ribcage, until he swears he can feel the bones creak in warning. “Ow, gimme some warning next time there, big guy. You're heavy.”  
  
He doesn't cringe, though, and he doesn't squirm in the hold, he just stands there and lets Sans hug him. Even pats his back a little bit, when the hug lingers for far too long.  
  
((That’s progress too. ))  
  
And really, what gets to Sans is the fact that he can’t stop it. He can't undo any of it. He can't ask Papyrus for an explanation, even, at least not right now.  
  
He can't _handle_ an explanation right now.  
  
He can _help_ though, he can do _something_ to begin repairing the damage done to his family. So even if he doesn't ask his initial question directly, this conversation is what cements his decision. It's what he carries with him as he's packing a few things into his backpack and considering first aid supplies and as he's sat at his desk, staring at the blank pages that will be his goodbye letter to his brother.  
  
There will be time, he tells himself, when this is all over and done with, when he has everyone together and safe, that he will be able to have this discussion with his brother. Without the ghost of Gaster breathing down their collective necks, it will be so much easier to let Papyrus fall apart when he knows they have the luxury of sparing the bandwidth to help put him back together.  
  
It’s kinder to remedy the worst of the fracture first, sometimes, so the damage can even begin to repair itself properly. Technically, everything that follows still counts as mercy.  
  
It’s kinder, sometimes, to hammer a broken bone back into place, heedless of how it might make the patient scream.  
  
  
  
  
  
  
  
  
  
  


**Notes for the Chapter:**

> some context for what exactly Red is on about and why baby edge is so crazy exists here in this adjacent story: 
> 
> [ everyone learns faster on fire ](https://archiveofourown.org/works/17236649)


	2. fuckin’ a

**Summary for the Chapter:**

> Blue makes some new friends

**Notes for the Chapter:**

> finally, the thing I’ve been nervous for: the actual universe crossover! the confusing dynamics! the _names_!
> 
> thank you to everyone who’s held on to this story in any way, and of course double thanks to everyone who’s responded: this is officially the most complete thing I’ve written since I was a little tiny child. 
> 
> I can’t promise many more next-day updates but I actually DO have this story planned out pretty completely and at least three more parts fully written. 
> 
> Blue meets the swapfell boys in this one, who have their own little corner of hell happening in [this story](https://archiveofourown.org/works/17626757)

# chapter one

* * *

_do you notice how my nails don't stay?_  
 _do you notice that my clothes don't change?_  
 ** _do you notice that my life is a motherfucking nightmare that pushes good things away?_**  
  
— prince daddy & the hyena, _fuckin’ a_  
  


* * *

  
  
  
When Sans opens his sockets, he’s sure for a brief and panicked moment that he’s gone blind.  
  
He turns out to be wrong on that point, thank the stars—once his vision has adjusted a bit, he can tell there's a slight but definite shift from the blank black of his closed sockets to the murky grey of a cavernous, yawning space, entirely empty of...well, of _anything_ save the dim glow of his own eyelights.  
  
It's a relief, sure, but it's not much of a comfort. His breath doesn't come any easier at the realization. It's good that he _can_ see, maybe—but it's also incredibly disconcerting that he doesn't appear to be in a place where there's anything _to_ see.  
  
His entire body aches.  
  
He’s lying on his side in a tight fetal position, knees bundled to his chest, cheekbone resting on what feels like damp concrete. The air is frigid and damp besides, nipping at his sore bones right through the quilting of his jacket. Sans allows himself a low groan through gritted teeth, and rolls onto his back.  
  
He pushes himself upright, wincing as his joints creak in protest. Even his _tailbone_ hurts, a dull throb right down to the marrow like he’s been curled up tense in that position for way too long, like he might running a low-grade fever besides. He feels hungover, almost, a cramping nausea taken up residence where his stomach should be.  
  
His backpack—his medical supplies, his carefully-curated rations, water, _everything useful he has in the world right now—_ is nowhere to be seen.  
  
 _That’s okay!_ he reassures himself, placing his palms flat on the ground and forcing in several deep breaths, holding, exhaling in strict eight-count. _That’s okay! You expected that._ The bag had been a long shot anyways, considering the other sans had brought nothing with him save the contents of his pockets, but still.  
  
Painkillers would have been _really_ nice.  
  
Sans wants, with all the survival instincts of a desperate and stupid child, to call out into the nothingness before him. More than that, he finds that he wants the answering call of someone who has any idea what the fuck is going on here.  
  
He bites his conjured tongue and gets to his feet instead—if there is anyone sharing this miserable prison with him, no reason to alert them to his presence yet.  
  
Except that careful movement is accompanied by a metallic _shk shk shk_ that echoes so loud in the emptiness, it actually makes him flinch. It's accompanied by a shifting of considerable weight around his cervical vertebrae, a strange kind of _something_ slithering cold and heavy down his sternum, over the empty hollow where his belly should be, down the ridges of his pelvis before clattering noisily to the floor.  
  
 _Shit._  
  
Sans doesn't really have a heartbeat, per se, but he can feel his soul jackhammering in his ribcage as he maps with shaking claws the metal ring locked around his neck. It sits just beneath the one he'd borrowed from the other sans, as though the spiked leather collar had been removed and then refastened over its more effective twin.  
  
A chain drapes down his chest, right between the aching curves of his ribs, cutting the star graphic on his tank top neatly in two. He's not sure how he didn't feel it before.  
  
Each link is nearly thick around as his littlest finger, solid steel and welded shut. It's the kind of tether that seems like it might be overkill even for Greater Dog, never mind his own comparably tiny size.  
  
Sans wraps a gloved hand around the chain and tugs at it hard, cringing as it grates along the concrete floor beneath him. _So much for the quiet_ , he thinks, but he seizes another handful and pulls anyways. Repeats the motion again and again and again because he’s trembling now, he’s terrified; this isn’t going the way he thought it would at all, and he genuinely just doesn't know what else to _do_.  
  
Waking up in a dumpster would have been far preferable to this.  
  
The chain trails along the ground dead ahead of him and disappears into the darkness, with no actual end goal in sight. It’s creepy. It’s straight out of the cheesy horror movies Papyrus adores. It sets off every single alarm bell inside his skull, but it’s not like he has any other possible leads to pursue, so unless he wants to just sit here in the dark until he dusts of old age, he's gonna have to follow the goddamn leash.  
  
((He resolutely does not think about the polished metal around his neck, devoid of any apparent locking mechanism. Doesn’t think about the fact that he has no way— _no_ _ide_ a—how to remove it.  
  
Doesn't think about the fact that _someone_ must have put it on him, right, so...he can't possibly be alone in the dark after all.))  
  
Sans doesn't have any real way of tracking how long he's been following the thing, much less how far. He hasn't been counting his steps. There's not a single landmark to orient him, no sound in the dark but the clanking of his chain and the lonely rapport of his boot heels on concrete. Looking back over his shoulder, he can't even tell which direction he'd started from.  
  
He tries checking the time on his phone only once, and receives these scrambled nonsense symbols all across the screen. They’re moving all on their own and deeply unsettling to watch, flickering alien things pulsing bright neons that just make him feel sicker and sicker the harder he squints at them. Scowling, he shoves the thing back into his pocket.  
  
No calling for help, then. The void’s made _that_ abundantly clear.  
  
It feels like an eternity putting one boot in front of the other before finally, _finally_ he sees a tiny pink glow way off in the distance. It's brighter than the other sans's magic by a considerable margin, much deeper, closer to a electric magenta than his dusky, unenthusiastic rose. Doesn't flicker the way his does, either—it stays solid and steady, an easy guiding light as Sans approaches.  
  
((He tries not to wonder if it's a coincidence that his tether seems to be leading him directly towards it.  
  
Knowing his luck, it probably isn't.))  
  
His chain, now that he can see it properly, has been covered in a chipped coat of blue. The paint looks weathered, very old, and _very_ close to the exact shade of bright aqua as his own eyelights. That observation isn’t reassuring in the slightest.  
  
He’d guessed what the pink light would be long before he got there, of course. His weeks spent with his doppelgänger—not to mention the entire goal of this little mission in the first place—had been more than enough to prepare himself to meet yet another familiar face. Likely his own, if recent experience was anything to go by.  
  
He had _not_ , however, expected to be stopped in his tracks before he got there by an apparently-completely-unrelated-to-his-mission Papyrus. He hadn’t expected to find quite this brutal an echo of his brother _anywhere_ , filthy and shirtless beneath an unzipped hoodie, hunched down on all fours, braced to spring and snarling at him like a rabid dog.  
  
The face is too familiar to be anyone else, though Sans can't say he's _ever_ seen his real brother's expression quite so twisted up in rage. He's baring his teeth at Sans, a thick rope of saliva glistening between each top and bottom incisor. All four of those teeth are capped with gold, the surface dented and uneven with wear, so oversized he doesn't seem to be able to even close his jaw properly.  
  
The excess slides slick down his chin and into the cracks blanketing the surface of his cervical vertebrae. It's mostly caught by a collar nearly as scuffed as the other sans's, though this one is black leather rather than filthy red, studded instead of spiked, no tag in sight.  
  
This Papyrus wears his collar much tighter too, Sans notes dimly as he holds a hand out palm-up, like the guy might sniff at it. Papyrus eyes him suspiciously instead, a warning growl rumbling from somewhere deep inside that big ribcage. He paces back and forth in front of Sans, creeping low along the concrete, looking for all the Underground like a caged tiger with its back to the wall. His empty black sockets are narrowed, fixed unwaveringly on Sans.  
  
It's not the most comfortable experience, if he's being honest.  
  
There are red, swollen marks creeping out from beneath the collar, a strangely even pattern to the bruising like...like maybe the inside of the collar is studded to match the outside. Like maybe he'd strained at it enough to nearly choke himself on the thing regardless, like he didn't really feel it at all.  
  
A chain nearly identical to Sans's hangs heavy around Papyrus's neck from a matching metal ring, painted a grubby orange to San's blue. There's more than enough slack to it for Papyrus to easily cross the distance between them, were he so inclined.  
  
Even crouched like that on all fours, he's still nearly as tall as Sans. Sans swallows once, hard. He takes a step back and holds up both hands this time, letting go of his own lead, palms out in surrender.  
  
  
“H-hey there buddy,” he says, wishing for approximately the millionth time in his life that he was capable of any facial expression besides his wide grin. The Papyrus doesn’t reply to his greeting at all, only narrowing his sockets suspiciously and slinking a cautious step closer.  
  
He growls again. Sans really, _really_ hopes it's not his imagination, but he thinks this one sounds maybe more curious than warning.  
  
“Yeah, o-okay man, that's—look, that's fine, I'll just fuck off back that way.” He jerks a thumb into the black nothing over his shoulder, though from the way the sharp motion makes Papyrus hiss, he's pretty sure his rambling isn't helping much. “I-I mean, this is your territory, that's cool, y'know, it's a, uh, a _really_ nice void you got here—”  
  
He’s cut off by a loud yelp from Papyrus, the orange chain suddenly snapping tight around his neck. Papyrus chokes, staggers and skids backwards, thrown off-balance by the sudden movement. He whips around, snarling wordlessly, orange light flaring in his empty sockets—but when the chain jerks taut once more, almost in warning, he seems to catch himself. He whimpers once, and goes quiet. He doesn’t stand up. He sinks even lower to the floor, actually, the strings of his hoodie coiling on the dirty concrete as he goes down flat on his belly.  
  
“BEHAVE.” As he approaches, the small monster holding the chain winds another loop of the thing around his forearm, probably the better to brace himself against Papyrus's brute strength.  
  
He's got the hood of his crop top pulled up and he's missing the gold tooth, but the face is a dead ringer for the sans back home otherwise, scars and all. Filed-down fangs gleam a cold pink in the glow of his enormous eyelights and although his smile is not terribly friendly, he holds out one hand in Sans's direction in clear greeting. His claws are done in bright purple, though a battered pair of black sneakers prevent Sans from checking whether or not the toes are painted to match. There’s a tiny heart carved just below his left eye and when he catches Sans staring at it, he winks.  
  
“YOU CAN CALL ME ESSFOUR,” the newcomer bellows by way of explanation. He pronounces it just like that, like it's a word all on its own rather than half his assignation. He's made no effort to hide the engraving on his forearm—looks like he may have added some decorative detail to it, actually. Sans would prefer not to consider how he'd cut the lazy spiraling vines himself, never mind the design on his face.  
  
Sans doesn't reach for his hand. Sans doesn't breathe, feels like, just stares blankly at the bare outstretched fingers, at the unfamiliar glint of heavy rings and nail polish, his soul thrumming and agitated in the back of his mouth.  
  
The new Sans— _Essfour_ , he reminds himself, only a little hysterically— eventually gets bored with waiting, rolls his eyelights and drops his arm back down to his side. He pulls on the chain again, tugging Papyrus a few awkward steps closer to him, until he can rest that same hand on his brother’s cracked skull.  
  
He traces one of the aforementioned fractures with a painted claw, grin twitching wider when Papyrus whimpers at the touch. His eyelights never leave Sans.  
  
“You're hurting him,” Sans says before he thinks about it, and his new doppelgänger—well, maybe it'd be more accurate to call him the other sans's doppelgänger, considering his tail and the strange shape of his feet—laughs, an unnervingly bright thing in the surrounding gloom.  
  
“AM I?”  
  
Papyrus's whole body snaps into a rigid line when the claw shoves _hard_ into the crack, deep into the glimmering honey-colored residual magic where his body is attempting to heal itself.  
  
Something that was supposed to be Papyrus's name catches in Sans's throat when, instead of pulling away from the pain like any _normal_ monster would do, Papyrus just tips his head back and pushes into Essfour's hand, insistant as a giant housecat. He _moans,_ even, low and throaty, and Sans can feel his own cheekbones flushing bright in secondhand embarrassment.  
  
This...seems like something he shouldn't be seeing, something Papyrus would have been ashamed of if he'd been present enough to understand. He doesn't seem to care much for Sans's discomfort though, happy to lounge against his brother's side. His sockets have dropped sleepily to half-mast, all the fight drained from him at the reassurance that someone else has this situation under control.  
  
“GOOD BOY,” Sans's newest counterpart murmurs, and Papyrus practically purrs, tipping his skull against the jut of his brother's hipbone, sharp above the waistband of his cutoff shorts. Sans's eyelights drop down to the bare concrete ground, and his new doppelgänger snickers meanly when he realizes. “SORRY, PRINCESS— TOO MUCH FOR YOUR DELICATE SENSIBILITIES?”  
  
He even talks like the sans back home, same vague, wry twist to his mouth, same gravelly kind of smoker’s growl, though his voice is much louder. Sans winces at how it rings in the stillness surrounding them, an uncomfortable instinct prickling at the base of his skull and insisting that there was _something_ that would hear them out there. Something listening.  
  
Something dangerous.  
  
“Could you...maybe tone it down a little?” he asks, gently as possible, because although Papyrus doesn’t seem so much inclined to tear him limb-from-limb anymore, this is far from a comfortable experience. He tries—politely, he thinks—to keep his eyelights trained on Essfour’s face rather than the slow strokes he’s trailing along Papyrus’s skull, like he’s petting an enormous cat.  
  
“Sorry,” his doppelgänger offers, in an admittedly somewhat quieter shout. “Can’t really hear how loud it is. Lab accident,” he explains when Sans’s brow wrinkles in confusion and lifts his free hand, snapping his claws next to his skull as if to demonstrate. “You know sign?” he asks almost hopefully, eyelights dimming a little in disappointment when Sans shakes his head.  
  
“No, I—I don’t, but I have a friend who does. Or...one of us? Another Sans,” he says, and Essfour chuckles.  
  
“Yeah the verbiage gets fucked pretty quick,” he agrees. “Is your buddy a swapverse Sans, too?”  
  
“Uh...no?” Sans ventures though he's really only half-sure about that answer. “Nah, he's—his magic is pink, same as yours. And he's got your weird feet. And a tail.”  
  
“Fellverse then,” Essfour says brightly. “That's always a fun crossover! Though I can't say I've seen many that would make good houseguests. How'd he wind up in your timeline?”  
  
Sans shrugs. He’s starting to feel a little dizzy. “Your guess is as good as mine, dude—we found him in a dumpster.”  
  
Essfour laughs, and he does it just like sans does, too loud and barking, like it’s been startled out of him. “That's on-brand, gotta give the guy that much. You trying to get him home, then?”  
  
“What?” Sans blinks, shakes his skull emphatically. “No, I—fuck, no, his timeline’s a _mess_. Don't you—I mean, aren't you from the same place, kind of? I mean, you look the same, I'm sorry to assume— ”  
  
Essfour tilts his skull. “No, that’s okay, it’s just...a big question. I guess if you're looking at the timelines in terms of how much the actual universes deviate from each other, yeah, we'd be from the same genre of shithole.” He shrugs. His eyelights drop just a little, just enough that he isn't looking at Sans properly anymore, hand stilled on Papyrus's skull. “None of them are pleasant, exactly, but ours is...bad.”  
  
“So you get why I don't wanna send him back.”  
  
“Ahhhh, you're one of those bleeding-heart types.” Essfour snorts, sounding distinctly unimpressed with the observation. “Just so you know, there's plenty of Sanses that straight-up skip that option. You're under no obligation to take care of him. Nothing happens to the 'verse if you don't.” His eyelights fix on his own claws curled around Papyrus's coronal suture and stay there. “It won't change anything.”  
  
If Sans knew him at all— if he was really even paying attention— he might see the way Essfour's smile goes brittle at that, shoulders hitching up ever so slightly. He might notice that Essfour's free hand balls into a tight little fist at his side. He might see Papyrus's skull tip up a few degrees towards his brother, brow wrinkled in concern.  
  
“He’s not an obligation,” Sans snaps though, so abruptly blind with rage that he misses every single one of those cues, so angry he hardly cares. “He's a _person,_ and like—I know we just met, so forgive my language, but fuck you _very_ much for suggesting otherwise.”  
  
“I never said— ”  
  
“I mean, is that what you would do?” Sans barrels on, taking a step towards his newest doppelgänger, heedless of how it makes his Papyrus bristle. “You’d just drop him back there, to keep fending for himself in the middle of—of his own _brothe_ r—doing _that_ to him—!” He chokes it off with a pained little sound. He’s guessing it’s only the dehydration keeping him from crying, with the way his sockets burn, but he can't find it in himself to be grateful.  
  
He sucks in a deep breath, composes himself. Asks, softly, “How can you live with that?”  
  
“No one helped me,” Essfour says, flat and bitter. Sans flinches. “No one helped Papyrus. We survived it alright. I mean, the particulars shift around a little bit between ‘verses, but it’s still a dance to the same old tune, you know? Gaster’s a real piece of work anywhere you find him.” He chuckles and resumes petting the crack in his brother's skull, eyelights flicking back up to Sans. His grin twists again, a little too wide. “And let's not pretend _you're_ doing great, pal. Just 'cause he didn't fuck you doesn't mean he didn't _fuck_ _you_ , you know what I mean?”  
  
And Sans does. Sans tries his hardest not to think about it most days but it’s always _there,_ right behind his eyelights, present enough that he’s long suspected it might be a problem, made worse by the other sans’s recent needling: three years, nine months two weeks and six days of his life, stolen from him before he was even old enough to conceptualize the loss.  
  
((Three years, nine months, two weeks and six days cramped up in a cage too small for him, his whole existence held entirely at the whim of a madman who couldn't quite decide if he needed Sans to survive the experience or not.  
  
Three years, nine months, two weeks and six days he _cannot think about_ if he at all wants to keep it together.))  
  
His hands are shaking. He shoves them into his sweatpants pockets and hopes the gesture looks casual. He tries not to think about how often he’s seen the same move replicated by his doppelgänger, and how the action was almost more of a tell than the trembling would have been.  
  
“I know what you mean,” he says softly. “I’m sorry, I don't mean to—”  
  
“Shut up,” his counterpart says, with no real malice. “Shut up, we’re not doing that right now. We’re talking about your guy. Is he just a Sans? What do I even call him? What do I call _you_?”  
  
It’s a clear and obvious deflection, but Sans lets him have it with no fight at all. He figures he owes the guy that much. “Whatever you want, man. I’m not too attached to the name.”  
  
“Hmm.” Essfour taps his jawbone with one claw. “Can I just call you ”Blue?“ Total transparency, I did a _buncha_ drugs as a kid and my short-term memory sucks. Color-coding keeps shit straight in my head a little better. You can be Blue, your buddy back home can be Red.”  
  
“Sure,” Sans allows, sockets crinkling in a smile. “He’s more of a rose pink though, if that matters to your system at all.”  
  
“No,” Essfour says gravely. “I don't call _any_ of them Pink. I learned that one fast.”  
  
“Toxic masculinity ruins the party again?”  
  
Essfour snorts out a laugh. “Something like that. And some of ‘em were coming off some _real_ bad resets, didn't take anything at all to set them off in my direction— ”  
  
“Resets?”  
  
Essfour freezes.  
  
“Shit,” he says, and Papyrus closes his sockets in something that looks an awful lot like a wince. Not for the first time, Sans wonders exactly how much of the conversation Papyrus has been able to follow. “I probably shouldn't have said that. You're from a swapverse. _Shit_. Look, just forget what I said dude. I did _so many drugs._ ”  
  
“Oh, no.” Sans crosses his arms over his chest firmly, brow furrowed into his very best approximation of a scowl. “You’re not gonna pull _that_ one on me, pal, not now. What’s a reset? What the hell does that even mean?”  
  
At Essfour’s feet, Papyrus gives a low whine. He’s seems kind of agitated, now that Sans is looking at him properly—he’s twisting around, trying to look behind him without dislodging his brother's hand on his skull. His frontal bone is damp with honey-colored sweat already, breath panting harshly through his teeth. Essfour's annoyingly-bright eyelights actually dim, just a little bit.  
  
From somewhere faint and far-off, Sans could swear he hears the rumble of thunder.  
  
“Don't talk about those here,” Essfour says, low and urgent, grabbing hold of Sans's jacket sleeve to tug him closer. They form a little huddle this way, the two of them, with Papyrus hiding in the middle best he can manage with his considerable size. “I'll answer whatever you want later when we're in my room and he can't hear us, but for right now I'm begging you, _please stop talking about them.”_  
  
“About the resets?” Sans asks, a bit snidely.  
  
“Yes!” Essfour snarls, opens his mouth like he’s really ramping up to yell, and then—  
  
“Dad,” Papyrus says. It’s the first word he’s spoken since they’ve met, and it’s alarmingly coherent. When Sans looks down, Papyrus is pulling at the ragged cuff of Essfour’s shorts, face poking around his legs to peer into the darkness behind them. He whines again. “I hear Dad, Ess, he sounds real mad. We gotta go.”  
  
“Fuck,” his counterpart hisses, head whipping around to check his six as well, though he doesn't relax in the slightest when he sees that there's no one there. “Fuck, okay, I—Blue, you're just gonna have to trust me for a minute here, alright? I'm gonna keep you alive, but you gotta do what I say, and we _super_ don't have time for questions.”  
  
“Okay,” Sans says, because that means they probably don't have time for an argument, either.  
  
The thunder peals again, louder now, and Papyrus makes a noise like a kicked dog.  
  
“Dope.” Essfour grabs Papyrus by the wrist, the one still pulling at his clothes, and shoves it towards Sans. “Hold his hand, make sure he doesn't run off without you. You'd never catch up.”  
  
Sans takes the offered hand—warm and a little damp, filthy from crawling around on the floor, but painfully familiar still in shape and size—and pointedly doesn't ask how Papyrus can possibly run on all fours, if he follows through with the command.  
  
Papyrus stands, instead, and Sans immediately wishes he hadn't. He's _massive_ even compared to Sans's own lanky brother, twice as broad in the chest and a good head taller. Holding his hand, Sans suddenly feels like the child in this equation. Papyrus doesn't help at all by threading his big fingers through Sans's own and giving them a reassuring squeeze.  
  
He doesn't have time to ask how, exactly, he's supposed to stop Papyrus from running anywhere, because Essfour's sinking his claws into midair, grimacing like the action is painful and ripping a glowing pink hole in—well, in _what,_ precisely, Sans can't be sure. The space beyond yawns black and emptier, somehow, than the concrete prison they currently occupy.  
  
He’s beginning to get a sinking feeling that they're going in the hole.  
  
Essfour grabs the edges in both hands and _pulls_ , his arms straining with the effort even in the absence of tightening muscle and tendon. It rips like a membrane, stretching and then splitting itself open, noiseless even as pink magic crackles like electricity all around the rim.  
  
Essfour’s phalanges are bleeding. He doesn't make a single complaint about it beyond a frustrated little grunt, though blood's dripping pretty enthusiastically down his wrists and trickling towards his elbows. “Get in!” he hisses over his shoulder, once he’s tugged open the rift wide enough to accommodate Papyrus’s bulk.  
  
Sans doesn't even have a chance to reply, doesn't have a chance to do anything but let out an undignified little squeak as Papyrus ducks beneath Essfour's arm and dives in headfirst, dragging Sans along behind him.  
  
The world goes black and silent immediately, like they've been dropped into deep water, and all Sans can feel in the dark is Papyrus’s warm, heavy hand holding on tight to his.  
  
  
  


**Notes for the Chapter:**

> referenced incest and rape/noncon but this is actually not a super horrifying chapter I think maybe? 
> 
> come yell at me at vstheworld.tumblr.com (SFWish) or morelikeskelesinstwopointoh.tumblr.com (NSFW)

**Author's Note:**

> warnings: referenced rape, referenced child sexual assault, grooming behavior, parent/child incest, referenced domestic violence, some light murder and also everyone is sort of an asshole a little bit 
> 
> please come yell at me at morelikeskelesinstwopointoh.tumblr.com or my SFW (ish) account, vstheworld.tumblr.com


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